Mucinous cystadenoma of appendix concomitant with perityphlic granuloma.

We describe a case of mucinous cystadenoma of the appendix with perityphlic granuloma. The patient developed a hard palpable mass in the right lower quadrant and barium enema induced irregular bowel wall at the cecum. Based on a preoperative diagnosis of carcinoma of the appendix, we performed a laparotomy. On operation, we found a tumor mass in the region of the appendix; the mass adhered strongly to the retroperitoneum and cecum. Right hemicolectomy was carried out on a diagnosis of carcinoma of the appendix. Microscopic examination revealed mucinous cystadenoma of the appendix with perityphlic granuloma. Mucinous cystadenoma in the appendix is a rare tumor. In this patient, the tumor was accompanied by granuloma formation in adjacent tissues because of mucin expelled from the appendix. This case emphasizes that granuloma formation can make of difficult to differentiate mucinous cystadenoma in the appendix from cancer.